Process and plant for manufacturing tires for vehicle wheels

ABSTRACT

Process and plant for the production of tires, in which lines ( 100 ) for assembling semifinished components in order to produce incomplete green tire structures ( 13 ) are combined with stations ( 200 ) for completing said structures laying down a continuous long element of crude elastomer material along a predetermined path so as to form a constituent element of the tire, for example tread band and/or sidewalls. This process envisages a step for temporarily storing the incomplete green tire structures ( 13 ) between the assembly line ( 100 ) and the completion station ( 200 ), performing mainly a “regulating” function so as to absorb the production of the assembly line when °; the latter is operative and constantly supply the completion station also when the assembly line is at a standstill.

The present invention relates to a process for the production of tiresfor vehicle wheels and to a plant which can be used to implement theabovementioned production process.

A tire for vehicle wheels generally comprises a carcass structurecomprising at least one carcass ply having respectively oppositeterminal edges folded around annular reinforcing structures normallyeach formed by a substantially circumferential annular insert on whichat least one filling insert is applied in a radially external position.

The carcass structure generally has, associated with it, a beltstructure comprising one or more belt layers situated radiallysuperimposed with respect to each other and with respect to the carcassply and having textile or metal reinforcing cords which have anintersecting orientation and/or are substantially parallel to thedirection of circumferential extension of the tire. A tread band, alsomade of elastomer material like other semifinished constituent parts ofthe tire, is applied to the belt structure in a radially externalposition.

It must be pointed out here that, in the context of the presentdescription and in the claims below, the term “crude elastomer material”is understood as meaning a composition comprising at least one elastomerpolymer and at least one reinforcing filler. Preferably, thiscomposition also comprises additives such as, for example, acrosslinking agent and/or a plasticizer. Owing to the presence of thecrosslinking agent, this material may be crosslinked by means of heatingso as to form the finished article.

Respective sidewalls made of elastomer material are also applied to theside surfaces of the carcass structure, each extending from one of thelateral edges of the tread band as far as the respective annularbead-reinforcing structure, whereby said sidewalls, depending on thedesigns, may have respective radially external terminal edgessuperimposed on the lateral edges of the tread band, so as to form aconstructional arrangement of the type usually known as “overlyingsidewalls”, or situated between the carcass structure and the lateraledges of the tread band itself, in a constructional arrangement of thetype known as “underlying sidewalls”.

In most of the known tire manufacturing processes it is envisaged thatthe carcass structure and the belt structure, together with therespective tread band, are manufactured separately from each other inrespective work stations and are assembled together subsequently. Moreparticularly, the manufacture of the carcass structure envisages firstlythat the carcass ply or plies are deposited on a first drum, usuallyreferred to as “building drum”, so as to form a cylindrical sleeve. Theannular bead-reinforcing structures are fitted or formed on the oppositeterminal edges of the carcass ply or plies, which are in turn foldedback around the said annular structures.

At the same time, an outer sleeve is manufactured on a second drum orauxiliary drum, said sleeve comprising the belt layers deposited in amutually superimposed radial arrangement and the tread band applied ontothe belt layers in a radially external position. The outer sleeve isthen removed from the auxiliary drum and joined to the carcass sleeve.The outer sleeve is, for this purpose, arranged coaxially around thecarcass sleeve, following which the carcass ply or plies are shaped in atoroidal configuration by moving the beads axially towards each otherand at the same time introducing fluid under pressure inside the carcasssleeve so as to cause application of the belt ring and the tread bandonto the carcass structure of the tire in a radially external position.Assembly of the carcass sleeve with the outer sleeve may be performed onthe same drum used for manufacture of the carcass sleeve, in which casereference is made to a “unistage building process”. A building processof this type is described, for example, in the patent U.S. Pat. No.3,990,931.

Alternatively, assembly may be performed on a so-called shaping drumonto which the carcass sleeve and the outer sleeve are transferred sothat building of the tire can be carried out in a so-called “two-stagebuilding process”, as described for example in the patents U.S. Pat. No.4,207,133 and EP 0 081 858.

In the conventional building methods, the tread band is normally madefrom a continuously extruded profiled part which, after being cooled inorder to stabilize its geometric shape, is stored on suitable platformsor reels. The semifinished product in the form of portions or acontinuous strip is then conveyed to a feeding unit which removes thesections or cuts, from the continuous strip, sections of predeterminedlength, each forming the tread band to be applied circumferentially ontothe belt structure of a tire being processed.

The document EP 1,211,057 A2 illustrates a method for manufacturing atire in which, during formation of a green tire, at least oneconstituent element such as a sidewall is formed by radially shapingoutwards a central portion of a substantially cylindrical carcassstructure and then winding around it a non-vulcanized rubber strip,joining the latter onto an external peripheral surface of the shapedcarcass structure.

The document EP 1,201,414 A2 describes a method for manufacturing a tirewhich comprises: assembling non-vulcanized rubber components so as toform a green tire, vulcanizing the green tire, and winding anon-vulcanized rubber strip around it so that the wound elements haveoverall a predetermined cross-sectional shape for at least one of thenon-vulcanized rubber components so as to form therefore at least one ofsaid non-vulcanized rubber components.

The Applicants have investigated the possibility of achievingsignificant improvements in terms of production flexibility and productquality by introducing, in conjunction with a process for the productionof tires by means of assembly of semifinished components, at least onestep involving manufacture of a constituent tire element made ofelastomer material, in particular a constituent element of the treadband and/or sidewalls, by winding a continuous long element along apredetermined path.

It must be pointed out that, in the context of the present descriptionand in the claims below, the term “incomplete green tire structure” ormore briefly “incomplete structure” is understood as meaning a greentire being processed, comprising a carcass structure having asubstantially toroidal shape associated with annular reinforcingstructures axially spaced from each other and optionally a beltstructure associated with this carcass structure in a crown zone andwithout at least one constituent tire element made of elastomermaterial. Preferably, said at least one constituent tire element ischosen from among: tread band, tread band underlayer, sidewalls andanti-abrasive strip.

In the context of the present description and the claims below, the term“semifinished components assembly line” or also, more briefly, “assemblyline” is understood as meaning a set of apparatus for building andsubsequently shaping incomplete green tire structures from semifinishedcomponents produced separately, stored and subsequently supplied to thebuilding machines; examples of these apparatus are the following:building drums (usually called “first-stage drums”), shaping drums(usually called “second-stage drums”), building and shaping drums(usually called “unistage drums”), drums for the production of beltstructures (usually called “auxiliary drums”), devices for transferringthe incomplete green tire structures, devices for transferring the beltstructures, machines. for manufacturing the semifinished products(comprising for example carcass plies, filling elements, belt strips,circumferential annular reinforcing inserts or “bead cores”), devicesfor storing the abovementioned semifinished products, and machines forsupplying the semifinished products to the abovementioned drums.

In the context of the present description and the claims below, the term“station (or also line) for completion laying down a continuous longelement” or also, more briefly, “completion station” or “completionline” is understood as meaning a set of apparatus for completing theabovementioned incomplete green tire structures, which compriseautomated devices for handling the said incomplete green tire structuresand devices for supplying and depositing a continuous long element ofcrude elastomer material. Completion is achieved by forming at least oneconstituent element of said tire, made of elastomer material, using theabovementioned continuous long element, below also called “elongatedelement”, produced in situ, i.e. shortly before formation of saidconstituent element of the tire, without stages involving storage of thesaid elongated element.

In order to achieve the abovementioned production flexibility, theApplicants have set themselves the goal of combining assembly lines, bymeans of which incomplete green tire structures are produced, withcompletion lines, by means of which at least one constituent tireelement made of elastomer material is formed so as to complete saidincomplete structures.

The combination of these different production lines has resulted in theneed to reconcile the varying productivity performance and the differentlevels of efficiency which are typical of these production lines, so asto combine a high productivity with a high level of efficiency ofproduction. In particular, the Applicants have ascertained that theassembly lines have a high productivity, i.e. a short cycle time (in theregion of 1 minute or even less), where “cycle time” is understood asmeaning the time required for manufacture of a part (in the specificcase, an incomplete green tire structure). The high productivity of theassembly lines is further increased owing to the fact that combinationwith the completion stations allows elimination, from the assemblyprocess, of the stages involving application of at least-one of theconstituent tire elements made of elastomer material, in particular thetread band and/or sidewalls. On the other hand the assembly lines have alevel of efficiency (i.e. a ratio between actual production time andprogrammed production time) which is fairly low, generally not greaterthan 60-70%, owing to recurrent machine stoppages resulting, forexample, from the need to change the reels supplying the semifinishedproducts and also malfunctions due to the high complexity of themachinery used. On the contrary, the lines for completion laying down acontinuous long element have a lower productivity, with cycle timesranging generally between 1.6 and 2.3 minutes, but at the same time ahigh efficiency (80-90%), with limited machine stoppages owing to therelative constructional simplicity of the machinery used and thecontinuous production of the elongated element, which therefore does notrequire storage reels.

The Applicants have found that it is possible to combine, in a singleplant, lines for assembly of semifinished components and lines forcompletion laying down a continuous long element, reconciling thevarying productivity performance and the different levels of efficiencyof the various lines, by means of a step involving temporary storage ofthe incomplete green tire structures between the assembly line and thecompletion station. This step involving temporary storage of theincomplete structures produced by the assembly line performs mainly a“regulating” function so as to be able to absorb the production of theassembly line when the latter is operative and constantly supply thecompletion station even when the assembly line is at a standstill.

The Applicants have also found that the abovementioned combination ofthe assembly line and completion line may be further improved byproviding a completion station which is able to process at least twoincomplete structures simultaneously. In this way it is possible toreduce the time spent by the incomplete green tire structures in thetemporary storage stage, owing also to the fact that the completionstation continues to be operative also during the stoppage times of theassembly line.

According to a first aspect, the invention relates to a process forproducing tires, comprising the following steps:

(i) in at least one assembly line, producing in sequence, incompletegreen tire structures having a substantially toroidal shape, theproduction of each incomplete structure comprising:

(i-a) building a carcass structure in the form of a substantiallycylindrical sleeve comprising at least one carcass ply operationallyassociated with annular reinforcing structures which are axially spacedfrom each other;

(i-b) shaping the carcass structure so as to have a substantiallytoroidal shape;

(ii) temporarily storing the incomplete structures produced by said atleast one assembly line;

(iii) transferring the incomplete structures to at least one completionstation;

(iv) in said at least one completion station, forming on each incompletestructure at least one constituent element of the tire laying down atleast one continuous long element of crude elastomer material along apredetermined path;

(v) subjecting the green tires thus produced to a vulcanization step.

According to a preferred embodiment, at least two incomplete structuresare processed simultaneously in a same completion station.

According to a preferred embodiment, at least two incomplete structuresare subjected simultaneously to the step (iv) involving the formation ofat least one constituent element of the tire in the same completionstation.

In the case where the tire to be produced also requires a beltstructure, in the process according to the invention the step (i) alsocomprises the steps of:

(i-c) manufacturing a belt structure;

(i-d) associating said belt structure with said carcass structure.

In this case, the step (i-d) of associating the belt structure with thecarcass structure may be performed before, after or at the same time asthe step (i-b) involving shaping of the carcass structure with asubstantially toroidal shape.

According to a further aspect, the invention relates to a plant forproducing tires, comprising:

at least one assembly line for the production of incomplete green tirestructures having a substantially toroidal shape, which comprises: atleast one apparatus for building carcass structures in the form of asubstantially cylindrical sleeve; and at least one apparatus for shapingsaid carcass structures so as to have a substantially toroidal shape;said carcass structures comprising at least one carcass plyoperationally associated with annular reinforcing structures axiallyspaced from each other;

at least one storage station for temporarily storing the incompletestructures produced by said at least one assembly line;

at least one completion station comprising: at least one member forsupplying a continuous long element of crude elastomer material; and atleast two units for handling the incomplete structures supplied by saidassembly line, said handling units being able to impart, to saidincomplete structures, a rotational movement about at least one axis ofthe incomplete structure and a translatory movement with respect to saidat least one supplying member, so as to form on said incompletestructures at least one constituent element of the tire laying down saidcontinuous long element along a predetermined path.

According to a further aspect, the invention relates to a station forcompletion of incomplete green tire structures, which comprises:

at least one member for supplying a continuous long element of crudeelastomer material;

at least two units for handling incomplete green tire structures, saidhandling units being able to impart, to said incomplete structures, arotational movement about at least one axis of said incomplete structureand a translatory movement with respect to said at least one supplyingmember, so as to form on said incomplete structures at least oneconstituent element of the tire laying down said continuous long elementalong a predetermined path.

According to a preferred embodiment, said completion station comprisesat least two members for supplying a continuous long element.

Further characteristic features and advantages will appear more clearlyfrom the detailed description of a preferred, but not exclusiveembodiment of a process and a plant for the production of tires forvehicle wheels in accordance with the present invention.

This description will be given here with reference to the accompanyingdrawings which are provided solely by way of a non-limiting example andin which:

FIG. 1 shows schematically from above a plant for the production oftires in accordance with the present invention;

FIG. 2 shows an elevation view of a completion station forming part ofthe plant according to FIG. 1;

FIG. 3 shows in schematic form a partial cross-sectional view of a tirewhich can be obtained in accordance with the present invention.

With particular reference to FIG. 1, 1 denotes in its entirety a plantfor producing tires in accordance with the present invention, whichcomprises an assembly line 100, a completion station 200 and a storagestation 300.

The invention is intended for the manufacture of tires in general, forexample tires of the type denoted overall by 2 in FIG. 3, comprisingessentially a carcass structure 3 with a substantially toroidal shape, abelt structure 4 extending circumferentially in a radially externalposition around the carcass structure 3, a tread band 5 applied to thebelt structure 4 in a radially external position, and a pair ofsidewalls 6 applied laterally onto the carcass structure 3 on oppositesides and each extending from a lateral edge of the tread band to a zoneclose to a radially internal edge of the said carcass structure.

Each sidewall 6 may have an associated radially external end portions 6aat least partially covered by the end of the tread band 5, as indicatedby the broken line in FIG. 5, in accordance with a constructionalarrangement of the type which is usually known as “underlyingsidewalls”. Alternatively, the radially external end portions 6a of thesidewalls 6 may be laterally superimposed on the corresponding ends ofthe tread band 5, as indicated by the continuous line in FIG. 5, 50 asto form a constructional arrangement of the type usually known as“overlying sidewalls”.

The carcass structure 3 comprises a pair of annular reinforcingstructures 7 which are incorporated in the zones usually referred to as“beads” and each composed, for example, of a substantiallycircumferential, annular, reinforcing insert 8—usually called “beadcores”—supporting in a radially external position an elastomer filling9. The terminal edges 10 a of one or more carcass plies 10 are foldedback around each of the annular reinforcing structures, said pliescomprising textile or metal cords extending transversely with respect tothe circumferential direction of the tire 2, if necessary with apredetermined inclination, from one to the other of the annularreinforcing structures 7.

In tires which are self-supporting or designed for special uses, it isalso possible to envisage auxiliary reinforcing inserts, for example ofthe type usually called “lunette”, applied in the vicinity of thesidewalls 6 on the inside of the carcass ply 10 or between two carcassplies joined together. As indicated by the broken line 11 in FIG. 5,these auxiliary elastic support inserts each have a radially internaledge 11 a arranged in the vicinity of one of the annular reinforcingstructures 7 and a radially external edge 11 b arranged in the vicinityof a side edge 4 a of the belt structure 4.

The belt structure 4 may, in turn, comprise one or more belt layers 12a, 12 b comprising metal or textile cords suitably inclined with respectto the circumferential extension of the tire, in respectivelyintersecting directions between one belt layer and the next, as well asan optional external belt layer 12 c comprising one or more cords woundcircumferentially in axially adjacent turns around the belt layers 12 a,12 b. Each of the sidewalls 6 and the tread band 5 essentially compriseat least one layer of elastomer material of suitable thickness. Thetread band 5 may also have, associated therewith, a so-called underlayer(not shown) of elastomer material having a suitable composition andphysical/chemical properties and acting as an interface between theactual tread band and the underlying belt structure 4.

The individual components of the carcass structure 3 and the beltstructure 4, such as in particular the annular reinforcing structures 7,the carcass plies 10, the belt layers 12 a, 12 b and any otherreinforcing elements intended to form the external belt layer 12 c, arefed to the plant 1 in the form of semifinished products produced duringprevious processing steps, so that they can be suitably assembledtogether.

The assembly line 100 comprises in general a building drum 14 on whichthe carcass ply or plies 10 are firstly wound, said ply or plies beingsupplied from a feeding apparatus 14 a (not described in detail since itmay be realized using methods well known in the art) along which theyare cut into sections of suitable length related to the circumferentialextension of the building drum 14, before being applied thereon so as toform a substantially cylindrical so-called “carcass sleeve”. The annularreinforcing structures 7 are fitted onto the terminal edges loa of theplies 10 and the said terminal edges are then folded back so as to causeengagement of the reinforcing structures inside the backfoldsconsequently formed by the plies 10. If required, the assembly line 100may comprise devices for associating with the carcass ply or plies 10auxiliary reinforcing inserts which are applied during preliminary stepsor inserted during the steps involving deposition of the ply or plies 10and/or other components of the carcass structure 3. In particular, it ispossible to envisage the application of the abovementioned auxiliaryelastic reinforcing inserts or “lunettes” 11 directly onto the buildingdrum 14 before application of the carcass ply or plies 10 or onto one ofthe carcass plies before application of an additional carcass ply 10.

Once assembly of the components has been completed, transfer devices(not shown). remove the carcass structure 3 from the building drum 14and transfer it onto a shaping drum 15.

Alternatively, assembly of the components of the carcass structure 3 maybe performed directly on the shaping drum 15, which therefore alsoperforms the function of a building drum: in such a case the drum 15 isof the type referred to as “unistage” and the carcass ply or plies 10supplied from the feeding apparatus 14 a and the annular reinforcingstructures 7 are assembled directly thereon, without therefore using thebuilding drum 14.

The belt structure is usually formed on an auxiliary drum 16 andsubsequently associated with the carcass structure 2. More particularly,it is envisaged for this purpose that the auxiliary drum 16 is able tointeract with devices 17 for application of the belt structure 4 whichmay, for example, comprise at least one feeding apparatus 17 a alongwhich semifinished products in the form of a continuous strip are fedand then cut into sections having a length corresponding to thecircumferential extension of the auxiliary drum 16 at the same time asformation of the corresponding belt layers 12 a, 12 b thereon. Anassembly (not shown in the figures) feeding one or more additionalreinforcing inserts, such as for example continuous cords to be appliedon top of the belt layers 12 a, 12 b so as to form the external beltlayer 12 c in the form of axially adjacent circumferential turns, mayalso be combined with the apparatus 17 a feeding the belt layers.

Upon actuation of suitable transfer devices, the belt structure 4arranged on the auxiliary drum 16 is disengaged from the latter andtransferred onto the carcass structure arranged in the form of acylindrical sleeve on the shaping drum 15. The transfer devices may forexample comprise a transfer member 18 with a substantially annular shape(commonly called “transfer device”) which is moved until it is arrangedaround the auxiliary drum 16 so as to remove the belt structure 4 fromthe latter. In a manner known per se, the auxiliary drum 16 disengagesthe belt structure 4 which is then moved by the transfer member 18 andarranged in .a coaxially centered position on the shaping drum 15supporting the carcass structure 3. It may be envisaged that the shapingdrum 15 is able to interact with the transfer member 18 following amovement of the shaping drum itself, from a position where it is able tointeract with the devices designed to engage the carcass structure 3thereon.

The carcass structure 3 is then shaped in a toroidal configuration bymoving the annular reinforcing structures 7 axially towards each otherand simultaneously introducing fluid under pressure therein so as tobring the carcass ply or plies 10 into contact with the internal surfaceof the belt structure 4 retained by the transfer member 18. A rollingstep, which can be performed in any suitable manner, may be carried outon the belt structure 4 after the shaping step or simultaneouslytherewith, so as to obtain better adhesion of the belt layers 12 a, 12b, 12 c against the carcass ply or plies 10.

Each incomplete green tire structure 13 is then transferred to a storagestation 300 and then to the completion station 200.

According to a preferred embodiment of the process according to theinvention, the incomplete structures 13 are disengaged from the shapingdrum 15 and placed manually or using automated transportation devices inthe storage station 300 adjacent to the completion station 200, pendingtransfer to the completion station 200.

According to an alternative embodiment, the incomplete structures 13 arekept on the shaping drum 15 and placed manually or using automatedtransportation devices in the storage station 300.

The storage stations 300 may comprise one or more manually operatedcarriages or one or more automatic or semi-automatic platforms(schematically shown in FIG. 1) on which the incomplete structures 13are arranged.

Transfer of the incomplete structures 13 to the completion station 200(where the incomplete structures being processed are indicated by 13 a,13 b) is preferably performed by means of the handling members 20 a, 20b (described in detail below) which remove in sequence each incompletegreen tire structure and subject it to the action of the supplyingmembers 19 a, 19 b, 19 c.

For this purpose, each handling member 20 a, 20 b is provided, at theend of the automated arm 21, with a support member 15 a, 15 b on whichthe incomplete structure 13 a, 13 b is supported and moved. The supportmember 15 a, 15 b may be formed, for example, by a drum on which the.incomplete structure 13 is transferred after each storage step. Thisdrum generally has a structure similar to that used for shaping (and ifnecessary also building) the incomplete structure itself.

Alternatively, the support member 15 a, 15 b is the same shaping drum 15on which each incomplete structure 13 a, 13 b has been shaped (and ifnecessary also built). In this case, as already mentioned above, afterthe assembly step, each incomplete tire structure 13 a, 13 b remainsengaged on its shaping drum 15 and is thus transferred to the storagestation 300 and then to the completion station 200 for application of atleast one constituent element of the tire. The shaping drum 15, oncedisengaged from the green tire 13 c obtained after completion, isbrought back to the assembly line 100 where it is reused in order toproduce another tire structure 13.

It should be commented that completion of the abovementioned green tirestructures 13 a, 13 b requires the application of at least oneconstituent element of the tire 2 such as, for example, the tread band,underlayer, sidewalls or anti-abrasive strip. Below, by way of example,only deposition of the tread band and the sidewalls is described, butusing the same procedures it is possible to deposit on theabovementioned incomplete tire structures all the constituent elementsof elastomer material necessary for completion of the abovementionedtire 2.

In accordance with the present invention, at least one of the stepsinvolving application of a constituent element of the tire, for examplethe tread band 5 and/or sidewalls 6, is performed by depositing at leastone continuous long element of crude elastomer material along apredetermined path, preferably in circumferential turns around ageometrical axis (preferably an axis of substantial radial symmetry) ofsaid incomplete tire structure.

Preferably, both application of the tread band 5 and application of thesidewalls 6 are performed using the abovementioned procedure, as will bedescribed more fully below. It is also possible, however, to form thesidewalls 6 in another manner, for example by means of an apparatus forfeeding the sidewalls (not shown in the figures), which is associatedwith the work station and designed to feed at least one semifinishedproduct in the form of a continuous strip of elastomer material, fromwhich the sidewalls themselves are cut in the form of sections ofpredetermined length depending on the circumferential extension of thebuilding drum 15 and the tire 2 to be obtained. The tread band 5 may inturn be directly produced against the belt structure 4 formed on theauxiliary drum 16, for example by means of an apparatus for feeding asemifinished product in the form of a continuous strip, from which thetread bands are obtained by means of operations involving cutting ofsections of suitable length.

In a preferred alternative solution, inside the said completion station200, at least two, more preferably three, supplying members 19 a, 19 b,19 c are present, said supplying members being each designed to deposita respective continuous long element of crude elastomer material ontothe incomplete structure 13 a, 13 b preferably in a position axially onthe outside of said carcass structure 3 and/or in a position radially onthe outside of said belt 4. Each supplying member 19 a, 19 b, 19 c mayfor example comprise an extruder, an application roller or other memberwhich, when positioned adjacent to the tire being processed, deliversand deposits the continuous long element of crude elastomer materialdirectly against the incomplete structure 13 a, 13 b, at the same timeas winding of the said long element about an axis of said incompletestructure 13 a, 13 b.

More particularly, at least one supplying member 19 a forming part of aunit for applying the tread band to the belt structure 4 in a radiallyexternal position is envisaged. The first supplying member 19 a may bedesigned to supply a first continuous long element directly against thebelt structure 4, so as to forn the tread band 5.

When the manufacture of the tread band 5 requires the formation of aso-called underlayer, a second supplying member 19 b may be envisagedfor depositing directly against the belt structure 4, before theintervention of the first supplying member 19 a, a second long elementintended to form the abovementioned underlayer of elastomer material.

A third supplying member 19 c, forming part of a unit for applyingsidewalls 6 to the carcass ply or plies 10 in an axially externalposition, is also preferably envisaged. The third supplying member 19 cis designed to supply a third continuous long element directly againstthe carcass ply 10.

In a different embodiment it is possible to envisage that theabovementioned three supplying members 19 a, 19 b and 19 c are intendedto form, respectively, a first tread band, a second tread band and thesidewalls. In this case the handling unit 20 a will bring the incompletestructure 13 a associated therewith into the vicinity of the members 19a and 19 c, while the handling unit 20 b will bring the incompletestructure 13 b associated therewith into the vicinity of the members 19b and 19 c. In this way it will be possible to perform simultaneousprocessing of two tires having for example tread bands composed of mixeswhich are different from each other.

In said completion station 200, each handling unit 20 a, 20 b interactswith the supplying members 19 a, 19 b, 19 c in order to produce themissing constituent element or elements, for example the tread band 5and/or sidewalls 6. Each handling unit 20a, 20b in fact operates asupport member 15 a, 15 b supporting said incomplete structure 13 a, 13b so as to cause it to rotate about its geometrical axis (preferably anaxis of substantial radial symmetry) so that each of the long elementsis distributed circumferentially with respect to the abovementionedincomplete structure 13 a, 13 b. Simultaneously, the handling unit 20 a,20 b performs controlled relative movements of the incomplete structure13 a, 13 b and the supplying member 19 a, 19 b, 19 c so as to distributethe long element in circumferential turns, thus forming the tread band 5and/or sidewall 6 in accordance with desired thickness and geometricalform requirements.

In a preferred constructional solution, illustrated in FIGS. 1 and 2,each handling unit 20 a, 20 b is incorporated in at least one automatedarm 21 carrying a terminal head 22 to which the support member 15 a, 15b is fixed in cantilever fashion, for example by means of a shank 29coinciding with its geometrical axis. In the example shown (FIG. 2), theautomated arm 21 comprises a base 23 rotatable on a fixed platform 24about a first vertical axis, a first section 25 constrained to the base23 in an oscillating manner about a second—preferably horizontal—axis, asecond section 26 constrained in an oscillating manner to the firstsection 25 about a third axis, which is also preferably horizontal, anda third section 27 rotatably supported by the second section 26 along anaxis perpendicular to the third axis of oscillation. The head 22 of theautomated arm 21 is constrained at the end to the third section 27, withthe possibility of oscillation about a fifth and a sixth axis ofoscillation which are perpendicular to each other, and rotatablysupports the primary drum 15 which can be rotationally actuated by amotor 28.

The automated arm 21 transports and suitably moves the incompletestructure 13 a, 13 b in front of the second supplying member 19 b (ifapplicable) intended for formation of the underlayer and, subsequently,in front of the first supplying member 19 a, upon actuation of whichformation of the tread band 5 is completed.

The incomplete structure 13 a, 13 b is then transferred to the thirdsupplying member 19 c and suitably moved in front of the latter in orderto perform formation of one of the sidewalls 6 laterally against thecarcass structure 3, roughly starting from the annular reinforcingstructure 7 as far as the corresponding lateral edge of the tread band 5previously formed. Following overturning of the incomplete structure 13a, 13 b in front of the third supplying member 19 c, formation of thesecond sidewall 6 is initiated, on the side of the carcass structure 3opposite to the sidewall 6 previously formed.

The operative sequence described above allows the formation of thesidewalls 6 with their radially external end portions 6 a laterallysuperimposed on the side edges of the tread band 5 in accordance with aconstructional arrangement of the type normally called “overlyingsidewalls”.

According to the invention it is possible to obtain, however, in anequally simple manner, formation of the sidewalls 6 in a constructionalarrangement of the type usually called “underlying sidewalls”.

For this purpose, immediately after engagement of the belt structure 4with the carcass structure 3, the incomplete structure 13 a, 13 b istransferred in front of the third supplying member 19 c in order tocarry out formation-of the sidewalls 6, before being brought in front ofthe second supplying member 19 b (if applicable) and the first supplyingmember 19 a in order to form the tread band 5. The opposite side edgesof the tread band 5 thus obtained will be superimposed on the radiallyexternal end portions 6 a of the sidewalls 6.

During the course of processing, each of the supplying members 19 a, 19b, 19 c remains preferably in a fixed position, while the incompletestructures 13 a, 13 b are made to rotate and suitably moved in atransverse direction by means of the automated arm 21 which operates thesupport member 15 a, 15 b so as to cause the distribution of eachcontinuous long element on the incomplete structure 13 a, 13 b so as tocompose a layer of suitable shape and thickness on top of the carcassstructure 3 and/or belt structure 4.

The continuous long element supplied by each of the supplying members 19a, 19 b, 19 c is preferably deposited in partially superimposed turnsand may advantageously have a tapered flattened section so as to be ableto regulate the thickness of the elastomer layer formed by varying thedegree of overlapping of the turns and/or the direction of the surfaceof the incomplete tire structure with respect to the cross-sectionalprofile of the long element supplied by the supplying member itself.

Once formation of the tread band 5 and the sidewalls 6 has beencompleted, the automated arm 21 again transfers the incomplete structure13 a, 13 b (which at this point is a complete green tire and will beindicated by 13 c) so as to move it away from the supplying members 19a, 19 b, 19 c and position it in front of devices which disengage thegreen tire 13 c from the support member 15 a, 15 b.

In the plant 1 according to the present.invention an unloading station400 is preferably envisaged, wherein the green tires 13 c, after beingdisengaged from the respective support members 15 a, 15 b, aretemporarily stored so that they can then be transferred to the finalmolding and vulcanization step (not described here in detail in that itmay be performed using techniques which are well-known in the art). Theunloading station 400 may be designed in a similar manner to the storagestation 300, as described above. In FIG. 1 the unloading station 400 isshown in broken lines and inclined with respect to the storage station300 only for the purposes of clarity of the drawing. The unloadingstation 400 may, for example, be arranged aligned with the storagestation 300 at a different vertical height so as to facilitate thehandling of the tire structures by the handling units 20 a, 20 b.

In accordance with the present invention, each completion station of theplant 1 is designed to perform simultaneously the processing of at leasttwo incomplete structures. For this purpose, as can be seen in FIGS. 1and 2, the completion station 200 envisages a first and a secondhandling unit 20 a, 20 b which move respectively a first and a secondincomplete tire structure 13 a, 13 b, each supported on a support member15 a, 15 b. In this way the incomplete structures 13 a, 13 b may bebrought sequentially into the vicinity of the supplying members 19 a, 19b and 19 c.

According to a possible embodiment, each completion station 200envisages that the supplying members 19 a, 19 b, 19 c are arranged insuch a way that the respective long elements of crude elastomer materialare supplied substantially at the same height with respect to thesupport surface of the completion station 200.

According to a preferred embodiment (as shown in FIGS. 1 and 2), thecompletion station comprises three supplying members 19 a, 19 b and 19c. Preferably two of them, for example the members 19 a and 19 b, arearranged so that the respective long elements made of crude elastomermaterial are supplied substantially at the same height, while the thirdsupplying member 19 c is arranged so that the respective long element ofcrude elastomer material is supplied at a height vertically higher thanthe height of the first two supplying members 19 a and 19 b, the heightsbeing defined with respect to the support surface of the completionstation 200.

According to a preferred embodiment, in the completion station 200, thesupplying members 19 a, 19 b and 19 c are arranged symmetrically withrespect to a same plane of vertical symmetry (indicated by “a” in FIGS.1 and 2). Preferably the handling units 20 a, 20 b are also arrangedsymmetrically with respect to the same plane of vertical symmetry “α”(see FIGS. 1 and 2).

In this way the handling units 20 a, 20 b inside the same completionstation 200 may simultaneously process two incomplete tire structureswithout problems of mechanical interference between them, reducing thetime required for completion of the green tires and consequently thetime spent by each incomplete structure inside the storage station 300.

Moreover, the simultaneous processing of at least two incompletestructures allows full use to be made of the machine stoppage time ofthe assembly line 100, which is longer than that of the completionstation 200, increasing the overall productivity of the plant 1 tovalues at least close to the productivity of the assembly line 100.

Moreover, as a result of the symmetrical arrangement of the supplyingmembers 19 a, 19 b and 19 c and the handling units 20 a, 20 b withrespect to the vertical plane of symmetry “α”, it is possible to managethe loading and unloading steps of the completion station 200 in adifferent area from that of the processing area (for example, as shownin FIG. 1, on opposite sides with respect to the handling units 20 a, 20b) and use the single storage station 300 (from which the incompletestructures are loaded) and a single unloading station 400 for both thehandling units 20 a, 20 b, with an obvious advantage for management ofthe plant 1.

Owing to the modular nature of the plant according to the presentinvention, it is possible to associate and manage effectively severalassembly lines and/or several completion stations and vary theconfiguration according to the production requirements. For example, inthe case where the production of high-quality tires (for examplehigh-performance tires intended for primary fitting) with a highproductivity is required, the plant 1 may be designed so that eachassembly line 100 has, associated with it, at least two completionstations 200. In this way the entire production resulting from theassembly line is completed laying down long elements as described above,so as to provide high-quality products with a low number of rejects.

On the other hand, if a standard production performance is required ofthe plant (for example intended for change-over) whereas the timeassigned to high-quality production is less compared to the totalproduction time, at least two assembly lines may be associated with eachcompletion station. In this case the completion station is programmed toreceive small batches supplied from the various assembly lines, whileeach assembly line is structured so that it is possible to complete thegreen tire structures with a tread band and/or sidewalls fromsemifinished products using traditional methods.

1-44. (canceled)
 45. A process for producing tires, comprising:sequentially producing incomplete tire structures in at least oneassembly line; temporarily storing the incomplete tire structures;transferring the incomplete tire structures to at least one completionstation; in the at least one completion station, forming at least oneconstituent tire element on each incomplete tire structure; andsubjecting completed tire structures to vulcanization; whereinsequentially producing the incomplete tire structures comprises:building a carcass structure in a form of a substantially cylindricalsleeve; and shaping the carcass structure so as to have a substantiallytoroidal shape; wherein the carcass structure comprises at least onecarcass ply operationally associated with annular reinforcingstructures, wherein the annular reinforcing structures are axiallyspaced apart from each other, and wherein forming the at least oneconstituent tire element comprises laying down at least one continuouslong element of elastomer material along a predetermined path.
 46. Theprocess of claim 45, wherein at least two incomplete tire structures areprocessed simultaneously in a same completion station.
 47. The processof claim 45, wherein at least two incomplete tire structures aresubjected simultaneously to forming the at least one constituent tireelement on each incomplete tire structure in a same completion station.48. The process of claim 45, wherein sequentially producing theincomplete tire structures further comprises: manufacturing a beltstructure; and associating the belt structure with the carcassstructure.
 49. The process of claim 48, wherein associating the beltstructure with the carcass structure is performed before shaping thecarcass structure so as to have the substantially toroidal shape. 50.The process of claim 48, wherein associating the belt structure with thecarcass structure is performed after shaping the carcass structure so asto have the substantially toroidal shape.
 51. The process of claim 48,wherein associating the belt structure with the carcass structure isperformed at a same time as shaping the carcass structure so as to havethe substantially toroidal shape.
 52. The process of claim 45, whereinbuilding the carcass structure is performed on a building drum, andwherein shaping the carcass structure is performed on a shaping drum.53. The process of claim 52, wherein before temporarily storing theincomplete tire structures, the incomplete tire structures aredisengaged from the shaping drum.
 54. The process of claim 45, whereinbuilding the carcass structure and shaping the carcass structure areboth performed on a same building and shaping drum.
 55. The process ofclaim 54, wherein before temporarily storing the incomplete tirestructures, the incomplete tire structures are disengaged from thebuilding and shaping drum.
 56. The process of claim 45, whereintemporarily storing the incomplete tire structures is performed in astorage station.
 57. The process of claim 45, wherein during forming theat least one constituent tire element, each incomplete tire structure issupported on a respective support member.
 58. The process of claim 57,wherein the respective support member comprises a shaping drum or abuilding and shaping drum.
 59. The process of claim 45, wherein formingthe at least one constituent tire element comprises laying down the atleast one long element in circumferential turns around an axis of theincomplete tire structure.
 60. The process of claim 59, wherein thecircumferential turns are partially superimposed.
 61. The process ofclaim 45, wherein the at least one constituent tire element comprisesone or more of sidewalls, a tread band, a tread band underlayer, and ananti-abrasive strip or strips.
 62. The process of claim 45, wherein theat least one constituent tire element comprises sidewalls and a treadband.
 63. The process of claim 45, wherein the at least one constituenttire element comprises sidewalls, a tread band, and a tread bandunderlayer.
 64. The process of claim 45, wherein during forming the atleast one constituent tire element, each incomplete tire structure ismoved inside the at least one completion station using a rotationalmovement about at least one axis of the incomplete tire structure and atranslatory movement with respect to at least one supplying member ofthe at least one long element.
 65. The process of claim 45, whereinafter forming the at least one constituent tire element, unvulcanizedtire structures are disengaged from a support member and temporarilystored before subjecting the completed tire structures to vulcanization.66. The process of claim 45, wherein the incomplete tire structuressupplied from an assembly line are transferred to at least twocompletion stations.
 67. The process of claim 45, wherein batches ofincomplete tire structures supplied from at least two assembly lines aretransferred to one completion station.
 68. A plant for producing tires,comprising: at least one assembly line for producing incomplete tirestructures; at least one storage station for temporarily storing theincomplete tire structures; and at least one completion station; whereinthe at least one assembly line comprises: at least one apparatus forbuilding carcass structures in a form of a substantially cylindricalsleeve; and at least one apparatus for shaping the carcass structures soas to have a substantially toroidal shape; wherein the carcassstructures each comprise at least one carcass ply operationallyassociated with annular reinforcing structures, wherein the annularreinforcing structures are axially spaced apart from each other, whereinthe at least one completion station comprises: at least one member forsupplying at least one continuous long element of elastomer material;and at least two units for handling the incomplete tire structures fromthe at least one assembly line; and wherein the handling units are ableto impart to the incomplete tire structures a rotational movement aboutat least one axis of respective incomplete tire structures and atranslatory movement with respect to the at least one supplying member,so as to form on the respective incomplete tire structures at least oneconstituent tire element by laying down the at least one long elementalong a predetermined path.
 69. The plant of claim 68, wherein the atleast one apparatus for building the carcass structures comprises abuilding drum.
 70. The plant of claim 68, wherein the at least oneapparatus for shaping the carcass structures comprises a shaping drum.71. The plant of claim 68, wherein the at least one apparatus forbuilding the carcass structures and the at least one apparatus forshaping the carcass structures are incorporated in a unistage drum. 72.The plant of claim 68, wherein the at least one assembly line comprisesat least one auxiliary drum for forming a belt structure.
 73. The plantof claim 72, wherein the at least one assembly line comprises at leastone transfer member for transferring the belt structure into a positionradially on the outside of a respective carcass structure.
 74. The plantof claim 68, further comprising: an unloading station for completed tirestructures from the at least one completion station.
 75. The plant ofclaim 68, wherein the at least one completion station comprises at leasttwo supplying members.
 76. The plant of claim 75, wherein the at leasttwo supplying members are arranged symmetrically with respect to a samevertical plane of symmetry.
 77. The plant of claim 76, wherein the atleast two handling units are arranged symmetrically with respect to thevertical plane of symmetry.
 78. The plant of claim 75, wherein a firstsupplying member and a second supplying member are arranged so thatrespective long elements of elastomer material are suppliedsubstantially at a same height.
 79. The plant of claim 78, wherein athird supplying member is arranged so that a respective long element ofelastomer material is supplied at a height vertically greater than thesubstantially same height of the first and second supplying members. 80.The plant of claim 68, wherein the at least one completion stationcomprises first, second, and third supplying members.
 81. The plant ofclaim 80, wherein the first supplying member and the second supplyingmember are arranged so that respective long elements of elastomermaterial are supplied substantially at a same height.
 82. The plant ofclaim 81, wherein the third supplying member is arranged so that arespective long element of elastomer material is supplied at a heightvertically greater than the substantially same height of the first andsecond supplying members.
 83. The plant of claim 68, wherein at leasttwo completion stations are associated with each assembly line.
 84. Theplant of claim 68, wherein at least two assembly lines are associatedwith each completion station.
 85. A completion station, comprising: atleast one member for supplying at least one continuous long element ofelastomer material; and at least two units for handling incomplete tirestructures; wherein the handling units are able to impart to theincomplete tire structures a rotational movement about at least one axisof respective incomplete tire structures and a translatory movement withrespect to the at least one supplying member, so as to form on therespective incomplete tire structures at least one constituent tireelement by laying down the at least one long element along apredetermined path.
 86. The completion station of claim 85, furthercomprising:. at least two supplying members.
 87. The completion stationof claim 86, wherein the at least two supplying members are arrangedsymmetrically with respect to a same vertical plane of symmetry.
 88. Thecompletion station of claim 87, wherein the at least two handling unitsare arranged symmetrically with respect to the vertical plane ofsymmetry.
 89. The completion station of claim 86, wherein a firstsupplying member and a second supplying member are arranged so thatrespective long elements of elastomer material are suppliedsubstantially at a same height.
 90. The completion station of claim 89,wherein a third supplying member is arranged so that a respective longelement of elastomer material is supplied at a height vertically greaterthan the substantially same height of the first and second supplyingmembers.
 91. The completion station of claim 85, further comprising:first, second, and third supplying members.
 92. The completion stationof claim 91, wherein the first supplying member and the second supplyingmember are arranged so that respective long elements of elastomermaterial are supplied substantially at a same height.
 93. The completionstation of claim 92, wherein the third supplying member is arranged sothat a respective long element of elastomer material is supplied at aheight vertically greater than the substantially same height of thefirst and second supplying members.